THE FUNDAMENTAL SUBSTRATES OF TASTE 131 



(Table 3). Thus a tenfold increase in concentration increases the recovery 

 time less than two times. On the other hand the recovery times after 0.03 M 

 Acoin and 0.3 m Alypin are both 40 to 45 min while the recovery times after 

 the weaker anaesthetics Anaesthesin and Tropacain are 15 to 30 min. 

 Thus, the recovery time depends more on the anaesthetic than on its 

 concentration. 



There are differences however among the four substrates. If one of the 

 substrates is only slightly susceptible to a certain anaesthetic, the recovery 

 time will be short. After application of 0.3 m Subcutin solution recovery 

 times for the bitter and salty substrates are 50 min, sour 45 min and sweet 

 35 min. However Alypin caused still more pronounced differences in 

 recovery times. Three minutes brushing-on of a 0.3 m solution in test 

 subject I yielded a recovery time for bitter of 45 min, salty 50 min, sour 5 

 and sweet 25 min. Similar, but not identical figures were obtained for the 

 three taste subjects. The complete recovery of the different substrates 

 never occured simultaneously. Thus one can conclude that the substrates 

 are largely independent, and the recovery time is shorter the less a specific 

 substrate has been affected by the anaesthetic. 



]n this connection the interesting observation was made that the complete 

 recovery to preanaesthetic conditions was often preceded by a period of 

 hypersensitivity. This condition is particularly dependent on the anaes- 

 thetic, the substrate and the individual. That the anaesthetic is of import- 

 ance is shown by the finding that hypersensitivity occurs after Subcutin, 

 Pantocain and Alypin, but never after Anaesthesin, Larocain, Stovain, 

 Psicain ok/ and ne\\\ Tropacocain, Eucain /A Holocain, Diocain. Acoin, 

 Percain and Eucupin. The bitter substrate often showed hypersensitivity 

 while the other three substrates seldom did. The salty substrate showed 

 hypersensitivity only rarely. The hypersensitivity is to no small extent a 

 matter of the individual. With many persons it was very pronounced, at 

 least for some substrates, while in others it was not found. 



C. It was of course desirable to determine whether a correlation exists 

 between the chemical structure of an anaesthetic and its effects on the 

 gustatory substrates. 



A strict correlation between the chemical structure and the effect on the 

 gustatory field has not been found. One gets the impression that substances 

 belonging to the amidines and the guanidines are more effective than those 

 belonging to other groups. The most potent were Pantocain, which is a 

 derivative of /;-aminobenzoic acid alkylaminester, and Acoin, which is a 

 guanidine derivative. In equal concentrations (0.03 m) Acoin is somewhat 

 more powerful than Pantocain, at least on the bitter substrate. 



It might be argued that the differences in susceptibility of the four 

 gustatory substrates could be due to an unequal depth of the receptors 

 beneath the tongue epithelium, as is the case with other sense modalities, 



